It is known that UVC radiation is effective in killing or deactivating pathogens in air, water and on exposed surfaces. UVC radiation is ultraviolet radiation having wavelengths in the shortwave C band and radiation in that band having a wavelength of 253.7 nm is reorganized to provide effective germicidal action. UVC lamps have been developed and are available for such germicidal or decontamination purposes. In general these lamps are low pressure, high output mercury or amalgam lamps.
It is also known that the operating temperature of UVC lamps affects their radiation output and that the lamps should be preferably cooled to provide efficient output. The optimum lamp operating temperature for low pressure, high output mercury lamps is 107° F. and for low pressure, high output amalgam lamps is 180° F. Lamp efficiency is especially important since electrical power for a UVC system is in most instances, limited to that available from standard 15A, 120 VAC wall outlets. Available power drawn is therefore limited to 1800W. However, known systems presently on the market, such as those listed in Appendix A hereto, have made no attempt to control lamp temperature to maintain lamp efficiency. It has been found that known systems suffer decreases in lamp output of about 60% or more as the lamps heat up, which can occur in a very short time of about 3 minutes.
Published application 2012/0305787 shows a surface disinfection system having a UVC lamp mounted on a portable base unit and contained within a transparent sleeve. Air from a variable speed fan is blown through the sleeve and the temperature of the lamp is measured and used to control the fan speed to maintain the lamp at an optimum operating temperature.
Published application 2003/0052279 shows a UV irradiation apparatus for decontaminating the surface of an object such as a semiconductor wafer. An array of UV lamps are arranged adjacent to a mirrored surface. The mirrored surface has openings of varying size to provide air flow in amounts to provide uniform cooling of the lamps.
U.S. Pat. Nos. 6,656,424 and 6,911,177 show an ultraviolet area sterilizer which employs a circular array of ultraviolet lamps on a movable dolly. Reflected radiation is measured at various locations in a room being irradiated and the lamps are turned off when the reflected light exceeds a predetermined level.
Despite the stated desire to control the temperature of UVC lamps in conventional systems such as those described in the references noted above, known systems have not attempted to achieve this stated object.
It would be beneficial to provide an ultraviolet radiation system for germicidal and decontamination purposes in which the UVC output is maintained at or near its maximum level without significant degradation in radiation output caused by heating of the lamps during operation and the same ultraviolet radiation can kill pathogens in the air in the room and on surfaces directly and indirectly radiated.